Microsoft: No Windows 8 ARM support for x86 apps

Linguistic jujitsu over ARM’s second class status

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Despite prior hints – and a Redmond developer conference that was all about app compatibility – Microsoft’s Steven Sinofsky has said that software for x86 Windows 8 systems will not run on ARM architecture.

For months, Redmond has promised that any code that ran on Windows 7 would run on Windows 8, with the expectation for many this included compatibility with ARM systems. But in a meeting Wednesday with financial analysts – transcribed on Microsoft's website – Sinofsky dashed these expectations. He insisted this wasn't a retreat from previous stances since Windows 7 doesn’t run on ARM systems, something that came as a surprise to the analyst asking the question.

It’s going to be a surprise for a lot of other people too. Just yesterday, Steve Ballmer was promising that on Windows 8’s launch there would be 500 million systems capable of running the OS, making it the world’s largest software market. What he chose not to mention was that the lack of compatibility for Windows 8 on ARM will mean significant developer time has to be spent porting applications for system on a chip (SOC) devices, relegating it to very much second class status among developers and consumers.

No doubt, Intel is also feeling a certain sense of vindication. In May, Intel software chief Renée James told investors that legacy Windows apps would not run on ARM platforms. Microsoft took the unusual step of publicly criticizing James, calling her statements “inaccurate and unfortunately misleading,” but declining to be specific.

In his briefing, Sinofsky said that battery life was a particular issue for applications running on ARM SOC hardware, and there were significant downsides to ensuring compatibility between these and x86 systems. Instead, he spun this as an opportunity for developers to make money on both markets, rather than a form of coding apartheid.

“If we allow the world of x86 application support like that, or based on what we call desktop apps in our start yesterday, then there are real challenges in some of the value proposition for system on a chip," he said. "You know, will battery life be as good, for example? Well, those applications aren't written to be really great in the face of limited battery constraints, which is a value proposition of the Metro style apps.”

“So, we have to be careful that we don't remove the value proposition for those applications. On the other hand, people would say, 'Oh, but you have to let them run because then there's that whole ecosystem.' And then if we do let them run, we just brought the perceived negatives of some of the ecosystem. So, people say, great, now it's easy to port viruses and malware and we'll port those.”

Later in the same meeting, Ballmer estimated that around 5 to 10 per cent of Windows 8 users would be using keyboardless systems, expected to be the prime vehicle for ARM hardware. That said, the Samsung fondleslab Microsoft gave out to attendees of its BUILD conference lacks a keyboard but carries the same x86 hardware specification as a top-flight laptop. Faced with running most Microsoft code or settling for what gets ported to ARM, it’s clear which most buyers, and developers, will choose. ®

Update: This story has been updated to make it clear that Microsoft says x86 Windows apps will not run on the ARM version of Windows 8.